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Biomedical subjects

C Fournier

Publications and source records attributed to C Fournier.

At least 109 records · Page 6Linked to original sources
PubMed1996

Human erythroid spectrin alpha subunit and its SH3 domain are sensitive to acidic Plasmodium falciparum proteolytic activity.

Many proteases play a crucial role in the Plasmodium intraerythrocytic life cycle. Spectrin depletion, one of the major events involved in parasite release from the red blood cell, results from proteolytic activities associated with the presence of the intracellular parasite. Here, we describe a new acidic proteolytic activity from Plasmodium falciparum, whose target is the alpha-subunit of human spectrin. Immunoblotting experiments with antibodies specific for the tryptic peptides of the alpha-chain and in vitro proteolysis tests on recombinant peptides from different regions of the spectrin alpha subunit demonstrated that cleavage sites for the parasite proteolytic activity were localized within the SH3 motif of the alpha-chain sequence. Remarkably, this Plasmodium protease activity on spectrin SH3 substrate was unable to cleave the SH3 from fodrin, a non-erythroid spectrin.

Animals↗
PubMed1996

Major histocompatibility complex markers and disease heterogeneity in one hundred eight patients with systemic onset juvenile chronic arthritis.

STUDY OBJECTIVES: Long term prognosis of systemic juvenile chronic arthritis range from full recovery to extremely severe crippling polyarthritis. An association between HLA-DR4 and a poor articular outcome has been reported. We studied the frequencies of class I, class II, and class III antigens according to clinical and laboratory test findings, particularly presence of antibodies to type II collagen, in a cohort of 108 patients. METHODS: A number of clinical and laboratory test findings were recorded at the time of the study. Class A, B, C, and DR antigens were assayed using a microcytotoxicity method. Antibodies to type II collagen were evaluated by ELISA. BMDP software was used for the statistical analysis. RESULTS: No significant differences in antigen frequencies were found between patients and controls for any of the loci. There were no significant differences in HLA-DR antigen frequencies between patients with favorable joint outcomes and those with chronic polyarthritis. CONCLUSION: Our findings do not corroborate those of earlier studies in smaller numbers of patients.

Arthritis, Juvenile↗
PubMed1995

Sequence analysis of a 33.1 kb fragment from the left arm of Saccharomyces cerevisiae chromosome X, including putative proteins with leucine zippers, a fungal Zn(II)2-Cys6 binuclear cluster domain and a putative alpha 2-SCB-alpha 2 binding site.

In the framework of the European BIOTECH project for sequencing the Saccharomyces cerevisiae genome, we have determined the nucleotide sequence of the left part of the cosmid clone 232 and the cosmid clone 233 provided by F. Galibert (Rennes Cedex, France). We present here 33,099 base pairs of sequence derived from the left arm of chromosome X of strain S288C. This sequence reveals 17 open reading frames (ORFs) with more than 299 base pairs, including the published sequences for ARG3, LIGTR/LIG1, ORF2, ACT3 and SCP160. Two other ORFs showed similarity with S. cerevisiae genes: one with the CAN1 gene coding for an arginine permease, and one with genes encoding the family of transcriptional activators containing a fungal Zn(II)2-Cys6 binuclear cluster domain like that found in Ppr1p or Ga14p. Both putative proteins contain a leucine zipper motif, the Can1p homologue has 12 putative membrane-spanning domains and a putative alpha 2-SCB-alpha 2 binding site. In a diploid disruption mutant of ORF J0922 coding for the transcriptional activator homologue, no colonies appeared before 10 days after transformation and then grew slowly. In contrast, haploid disruption mutants showed a growth phenotype like wild-type cells. One ORF showed weak similarity to the rad4 gene product of Schizosaccharomyces pombe and is essential for yeast growth. Five ORFs showed similarity to putative genes on the right arm of chromosome XI of S. cerevisiae. Two of them have similarity to each other and belong to a family of extracellular proteins that groups mammalian SCP/Tpx-1, insects Ag3/Ag5, plants PR-1 and fungi Sc7/Sc14.(ABSTRACT TRUNCATED AT 250 WORDS)

Chromosomes, Fungal↗
PubMed1995

Polyvinyl alcohol-coated macroporous polystyrene particles as stationary phases for the chromatography of proteins.

A method is described for the hydrophilization of macroporous poly(styrene-divinylbenzene) (PS-DVB) beads by adsorption of polyvinyl alcohol (PVA). PVA adsorbs strongly to PS-DVB surfaces but partially desorbs when exposed to protein solutions. To overcome this problems, the polymeric adsorbed layer was stabilized by crosslinking. We report the effect of polymer adsorption and crosslinking conditions on the amount of adsorbed PVA, on the stability of the polymeric layer and on the hydrophilization efficiency with regard to bovine serum albumin-a strongly hydrophobic protein. The properties of the coated supports were also evaluated by size-exclusion chromatography. PVA coating was shown to greatly reduce hydrophobic interactions. The pore size of modified PS-DVB particles was found to decrease significantly with increasing amounts of adsorbed PVA.

Absorption↗
PubMed1995

Biphasic effect of interferon-gamma in murine collagen-induced arthritis.

Interferon-gamma (IFN-gamma) exerts both enhancing and suppressing influences on collagen-induced arthritis (CIA), depending on the route and protocol of administration. To study the role of IFN-gamma on the autoimmune process of CIA, we treated DBA/1 mice with two different rat monoclonal antibodies (mAb) to murine IFN-gamma. Treatments, given twice weekly for 4 weeks, consisted of intraperitoneal injections of either mAb. In early treatments, starting from the day of immunization with type II collagen (CII), the severity of arthritis was reduced in both groups of anti-IFN-gamma-treated mice compared with control groups. Moreover, anti-CII antibody levels decreased in the sera of these mice. CIA was also down-regulated in mice treated from days 14 or 28 post immunization. In contrast, late treatments with anti-IFN-gamma mAb either induced aggravating effects, or did not affect the course of the disease. On the other hand, administration of high doses (8 x 10(4) U three times/week) of rat recombinant IFN-gamma exerted a transient increase of CIA severity. These findings suggest that IFN-gamma may play a critical role during both the induction and the course of CIA, first enhancing the immune response, and then regulating the arthritis process.

Animals↗
PubMed1995

Processing and presentation of type II collagen, a fibrillar autoantigen, by H-2q antigen-presenting cells.

Native type II collagen (CII) is a high molecular-weight fibrillar molecule which induces a chronic polyarthritis in mice expressing the H-2q haplotype. The present study was initiated to analyze the processing and the presentation of this nonglobular protein by H-2q antigen-presenting cells (APC). Efficiency of presentation was assessed by the ability of antigen-pulsed APC to activate collagen-specific CD4+ T cell hybridomas. Fixation of APC or the presence of chloroquine completely blocked the reactivity of the T cell hybrids to native, denatured and cyanogen bromide (CB) degraded CII, thus indicating the requirement of intracellular processing for adequate presentation of CII peptides to T cells. In the presence of various processing inhibitors (brefeldin A, leupeptin and N-tosyl-L-phenylalanine chloromethylketone) stimulation of T hybrids by CII-pulsed APC was reduced, pointing to the need of newly synthesized class II molecules, the use of several intracellular compartments and the implications of different proteases in the generation of CII peptides. Peritoneal macrophages and, to a lesser extent, total spleen cells, presented native and denatured CII with higher efficiency than purified splenic dendritic cells, naive or even immune B cells from CII-primed mice. In contrast, these dendritic and B cells were fully competent to present intact ovalbumin to a specific T cell hybrid. The stimulation by dendritic cells and immune B cells was greater when CB peptides of CII were added instead of the native molecule. Similarly, the cleavage of CII was an absolute requirement for its presentation by epidermal cells and B cell lymphomas to the T cell hybridomas. Taken together, these findings emphasize the crucial role of intracellular processing for recognition of soluble CII, similar to most antigens. However, in contrast to ovalbumin, the size and fibrillar nature of the native CII molecule influences its capture by the APC, thus limiting the type of APC able to present this antigen.

Animals↗
PubMed1995

Evaluation of a broth microdilution antifungal susceptibility test with a pH indicator: comparison with the broth macrodilution procedures.

A broth microdilution antifungal susceptibility test with a pH indicator (bromocresol purple) in a synthetic medium was evaluated. This method measures cellular activity instead of simply a change in biomass. The variations of pH caused by fungal activity were measured by changes in optical densities at 450 nm. The MICs50 obtained were compared with the MICs found by the classical broth macrodilution procedure. In most cases broth micro- and macrodilution MICs were in agreement for amphotericin B, fluconazole, flucytosine and nystatin.

Amphotericin B↗
PubMed1995

Long-distance and long-term follow-up of a patient with intermittent Cushing's disease by salivary cortisol measurements.

Salivary cortisol is an excellent indicator of the plasma free cortisol concentration in normal and pathological situations. We took advantage of its ease of sampling, allowing multiple collections at home, to follow the course of a patient with Cushing's disease living in North Africa. This 48-year-old woman presented with a clinically moderate hypercortisolism caused by a large basophilic pituitary adenoma. Bilateral extension to the cavernous sinuses precluded surgical therapy. She went into spontaneous remission based on clinical signs as well as biochemical findings. During the following 2 years she demonstrated intermittent relapses that were treated by radiotherapy (50 Gy), followed by ketoconazole and then o-paraprime-dichloro-diphenyl-dichloroethane (Op'DDD). After a prolonged clinical remission, Cushing's syndrome again became active. Bromocriptine was started without effect and a new treatment with Op'DDD was began. Evaluation and follow-up were performed during hospitalizations and mainly through the measurements of salivary cortisol in more than 100 samples sent from North Africa by air mail to our department in Paris. Thus we were able to demonstrate intermittent overproduction of cortisol before any treatment, with periods of normal and even low values, and to follow the efficacy of therapy and to detect the relapses. We conclude that measurement of salivary cortisol is a valuable tool in difficult clinical situations such as intermittent hypercortisolism and remoteness between the patient and hospital.

Africa, Northern↗
PubMed1995

[Hypercalcemia and squamous cell carcinoma of the upper respiratory-digestive tracts. Incidence and prognosis].

We performed a retrospective analysis on all head and neck cancers with hypercalcemia seen between January 1988 and June 1993 at the Centre Oscar-Lambret, cancer center of northern France. Hypercalcemia, non albumin-corrected, higher than 2.60 mmol/l was observed in 173 of 3,394 consecutive patients (5%). Median age of patients with hypercalcemia was 53 years and 97% of these patients were males. All patients with hypercalcemia had advanced or recurrent and/or metastatic squamous cell carcinoma of head and neck (SCCHN); 31 of them were not pretreated. There was no significant difference in histology between patients with or without hypercalcemia, but hypercalcemia was most commonly associated with lesions of the oropharynx (p = 0.00001). The median of calcemia was of 2.83 mmol/l (2.61-4.70). Gastrointestinal and neurologic symptoms respectively occurred in 24% and in 14% of patients and bone metastases in 25% of patients. Median survival after the first determination of hypercalcemia was of 7 weeks (0-128) for the overall group of 173 patients and of 12 weeks (1-128) for those 31 patients with hypercalcemia at initial diagnosis. Prognosis associated factors were: efficacy of antitumour treatment, performance status and hypercalcemia superior or not to 3 mmol/l. We concluded that hypercalcemia in head and neck cancer is usually a late manifestation associated with advanced, recurrent and/or metastatic disease and carries a poor prognosis. The prolongation of survival can be obtained in some patients if an effective antitumour treatment is feasible.

Adult↗
PubMed1995

[Treatment of inflammation with anti-inflammatory cytokines: example in models of auto-immune diseases].

Cytokines may exert anti-inflammatory properties, allowing the hypothesis of their potential therapeutic use. Targeting the cytokines balance may modify the course of subsequent inflammatory events in an autoimmune disease. Many data are available. Interferon-gamma can be blocked by an anti-interferon-gamma monoclonal antibody: if the treatment is administered in the early phase of an autoimmune disease such as collagen-induced arthritis, the course of the disease is worsened; if the treatment is given later, the disease can be improved; these results are mirrored by treatment with high doses of the cytokine itself. Pharmacologic effects of antiinflammatory cytokines such as interleukin (IL)-4, IL-10 or IL-13 are a protection against several experimental autoimmune diseases. The very short half-life of cytokines makes them difficult and expensive to use directly; in such occurrence, high quantities have to be frequently injected. In this context, gene therapy appears as an effective alternative solution: the transfection of cells with cytokines genes (e.g. either IL-4 or IL-13) then the engraftment of these vectors in animals, permit the in vivo secretion of high levels of cytokines, and result in the protection of the animals from the development of the disease.

Animals↗
PubMed1995

Randomized trial comparing conventional intravenous bolus FEC and FEC with high-dose infusional 5-fluorouracil as first-line treatment of advanced breast cancer.

FEC (5-FU 500 mg/m2, epirubicin 50 mg/m2, and cyclophosphamide 500 mg/m2) administered as a conventional bolus schedule is widely used in treatment of advanced breast cancer. 5-FU is thought to be more efficient when administered at high doses as a continuous infusion. The aim of this study was to compare the response rate, time to treatment failure, and overall survival obtained with standard FEC regimen (group A) and FEC with high-dose infusional 5-FU (750 mg/m2 per day/days 1 to 5) (group B). One hundred and seventy-eight patients entered this study, 89 in each arm; 10 were noneligible. Both groups were comparable for age, performance status, menopausal status, hormonal receptor status and prior treatment of the initial tumor, duration of relapse free interval, and type and number of disease sites. One hundred and forth patients were evaluable for efficacy. The response rate was 33.3% in group A (1.4% complete response-CR), and 39.4% in group B (9.8% CR) (ns). In an intent to treat basis (n = 168) the response rates were 26.8% and 34.1%, respectively, in groups A and B (ns). The response rate in liver metastasis was significantly higher in group B (57.1%) than in group A (20.0%) (P = 0.03). The time to treatment failure and overall survival were not different between the two groups. One hundred and fifty-three patients were evaluable for toxicity. 10.7% of the patients in group A and 16.0% in group B stopped treatment due to toxicity. Stomatitis was more frequently observed in group B than in group A (46.7% versus 2.6%, respectively, p < 10(-9)). The rates of other side effects were similar in the two groups. In conclusion, the two regimens gave similar overall response rates, time to treatment failure and survival, but infusional 5-FU yielded a better response rate in the liver metastasis.

Adult↗
PubMed1994

Interleukin-1-induced prostaglandin E2 biosynthesis in human synovial cells involves the activation of cytosolic phospholipase A2 and cyclooxygenase-2.

Treatment of human synovial cells with interleukin-1 (IL-1) results in a large increase in the production of prostaglandin E2 (PGE2), a function in which the activation of phospholipase A2 (PLA2) is a key step. In order to identify the enzymes that are linked to IL-1-mediated arachidonate availability and subsequent PGE2 production, we have investigated the changes in gene expression of the 85-kDa cytosolic PLA2 (cPLA2), the 14-kDa secretory PLA2 (sPLA2) and the two forms of cyclooxygenase in human synoviocytes after stimulation with recombinant IL-1 beta. Northern-blot analysis revealed that both cPLA2 and cyclooxygenase-2 mRNA were progressively upregulated upon exposure to IL-1 for 5 hours and the glucocorticoid, dexamethasone, blocked the increased expression of these two genes. In contrast, IL-1-induced sPLA2 gene expression determined in the same cell samples was weak and most often rapid, and dexamethasone further stimulated it. In addition, IL-1 did not modify the levels of the constitutive cyclooxygenase-1. The cPLA2 and cyclooxygenase-2 enzymic activities are dependent upon de novo synthesis of mRNA and protein, since they were inhibited by actinomycin D and cycloheximide. Our data suggest that the IL-1-induced production of PGE2 in human synoviocytes can be attributed to the stimulation of both cPLA2 and cyclooxygenase-2. These enzymes may represent appropriate targets for selective blockade of prostanoid production in the inflammed joints.

Cells, Cultured↗
PubMed1994

IL-1 beta amplifies bradykinin-induced prostaglandin E2 production via a phospholipase D-linked mechanism.

The proinflammatory cytokine IL-1 was shown to increase the responsiveness of synovial cells to the potent inflammatory peptide bradykinin (BK). We have investigated the biochemical events linked to this amplifying action of IL-1. Stimulation of synoviocytes with only BK elicited a rapid increase in inositol phosphates and a concomitant accumulation of diacylglycerol (DAG), monoacylglycerol, and free arachidonic acid (AA). In contrast, IL-1 did not stimulate any of these events. Thus, BK can induce AA release via the hydrolysis of phosphatidylinositols by a phospholipase C (PLC). BK also activated a phospholipase D (PLD) to cleave phosphatidylcholine (PC), because it caused an increase in phosphatidic acid (PA) content and a sustained DAG formation, which both were inhibited by ethanol in [3H]myristic acid-labeled cells. Moreover, the addition of ethanol diverted PLD into the formation of phosphatidylethanol (PEt) thus inhibiting the amounts of PA and DAG formed. Priming of synovial cells with rIL-1 beta 24 h before exposure to BK in the presence of ethanol further enhanced the BK-induced formation of PEt. Conversely, preincubation with IL-1 did not influence the BK-induced PLC activation nor did it alter the liberation of AA. Finally, we demonstrated that the IL-1-mediated amplification of PGE2 release in response to BK was reduced by the presence of ethanol in the culture medium, suggesting that part of the synergistic action of IL-1 and BK on prostanoid production was dependent on the activation of the PC-specific PLD pathway.

Bradykinin↗
PubMed1994

[Rheumatoid polyarthritis. Immunopathological mechanisms, contribution of experimental arthritis].

Rheumatoid arthritis is an auto-immune disease the autoantigen of which has not yet been identified. Induction and maintenance of the disease may involve environmental factors (bacteria, viruses) and autoantigens directly issued from the articular tissue (collagens, proteoglycans). T cells play a crucial role in rheumatoid arthritis; after the antigen has been recognized, they secrete lymphokines and enable other T and B lymphocytes to be activated. The synovial cells themselves can produce large amounts of lymphokines and enzymes which contribute to the destruction of joints. The immunopathology of rheumatoid arthritis is now much better known owing to studies of experimental arthritis which are the animal models of the disease. These models have helped in validating therapeutic approaches based on immunointervention.

Animals↗
PubMed1994

Comparative pharmacokinetics of oxaliplatin (L-OHP) and carboplatin (CBDCA) in mice with reference to circadian dosing time.

Carboplatin (CBDCA) and oxaliplatin (I-OHP) are non-nephrotoxic platinum (Pt) compounds, which exert their main respective toxicities on the bone marrow and on the intestinal mucosa in mice. Plasma and red blood cell (RBC) drug dispositions were investigated in 324 male B6D2F1 mice after a single IV injection of CBDCA (72 mg kg-1) or I-OHP (17 mg kg-1). Since the toxicities of either drug largely depended upon circadian dosing time, such a pharmacokinetic study was performed following injection of either Pt complex at a time of low (16 h after light onset-HALO), intermediate (0 HALO) or high (8 HALO) toxicity. Pt concentrations in plasma ultrafiltrate (PUF) and in total plasma declined in parallel and became barely detectable by 2 h following CBDCA injection. Conversely, free Pt became undetectable 1 h after I-OHP injection, whereas sustained levels of total Pt were found 24 h post dosing. This suggested that I-OHP had a high binding affinity for plasma proteins. Mean values of t1/2 alpha and mean residence time (MRT) of free Pt for I-OHP (6.7 min and 9.7 min respectively) were half those of CBDCA (12.5 min and 18.1 min respectively). The two drugs had a similar initial volume of distribution (Vdi) of free Pt (10.5 mL) in mice. However, plasma clearance of I-OHP was twice as high (1.06 mL min-1) as that of CBDCA (0.58 mL min-1). Free Pt AUCs were eight to ten times lower for I-OHP than for CBDCA. In contrast, erythrocyte Pt AUCs were three to four times as high for I-OHP as for CBDCA. Circadian changes in pharmacokinetic parameters were large, yet limited to the initial distribution phase (C0, t1/2 alpha, Vdi) as well as mean residence time. The smallest Vdi and the fastest plasma elimination occurred when either drug was injected at 0 HALO. The largest Vdi and the longest elimination were however observed at 8 HALO for CBDCA and 16 HALO for I-OHP. No consistent relationship was found for both Pt complexes with regard to circadian changes in blood pharmacokinetics and in target organ toxicities. The major pharmacokinetics differences between CBDCA and I-OHP were related to both protein binding and RBC handling.

Animals↗
PubMed1994

T cell regulation of collagen-induced arthritis in mice. III. Is T cell vaccination a valuable therapy?

Since T cells play a critical role in collagen-induced arthritis (CIA), CD4+ T cell hybridomas were derived from DBA/1 mice immunized with bovine type II collagen (CII). The hybrid clones selected were Thy-1-2+, CD4+, CD8-, T cell receptor (TcR) alpha beta + and produced interleukin-2 in response to CII peptides presented by I-Aq molecules. The clones were collagen type-specific and recognized CII from many species except the mouse. More precisely, the reactivity was directed against the immunodominant cyanogen bromide-cleaved fragment CB11(II). Analysis of the TcR carried by the T cell hybridomas showed that they used identical V alpha and J alpha (V alpha BMB, J alpha 20) gene segments and two distinct V beta (V beta 1 and V beta 4) associated with the J beta 2.5 gene segment. Interestingly, the junctional regions were highly conserved in structure and length. These findings may indicate a strong in vivo selection by the antigen for a particular combination of both alpha and beta chains of the TcR. Inoculation of irradiated anti-CII T cell hybrids into DBA/1 mice, before priming with CII, altered the course of the disease resulting in either a long-lasting suppression or an exacerbation of CIA whereas a control CD4+ hybridoma with an unrelated specificity did not influence the development of arthritis. However, the regulatory effect of anti-CII T cell clones was unpredictable, suggesting that the TcR structure may not solely account for the modulation of CIA and that T cell vaccination is not a reliable method for inducing suppression of CIA.

Amino Acid Sequence↗
PubMed1994

Effects of lipoprotein(a) on the binding of plasminogen to fibrin and its activation by fibrin-bound tissue-type plasminogen activator.

Molecular assembly of plasminogen and tissue-type plasminogen activator (t-PA) at the surface of fibrin results in the generation of fibrin-bound plasmin and thereby in the dissolution of a clot. This mechanism is triggered by specific interactions of intra-chain surface lysine residues in fibrin with the kringle domains of plasminogen, and is further amplified via the interaction of plasminogen kringles with the carboxy-terminal lysine residues of fibrin that are exposed by plasmin cleavage. By virtue of its marked homology with plasminogen, apo(a), the specific apolipoprotein component of Lp(a), may bind to the lysine sites available for plasminogen on the surface of fibrin and thereby interfere with the fibrinolytic process. A sensitive solid-phase fibrin system, which allows the study of plasminogen activation at the plasma fibrin interface and makes feasible the analysis of products bound to fibrin, has been used to investigate the effects of Lp(a) on the binding of plasminogen and its activation by fibrin-bound t-PA. Plasma samples from human subjects with high levels of Lp(a) were studied. We have established that Lp(a) binds to the fibrin surface and thereby competes with plasminogen (Ki = 44 nM) so as to inhibit its activation. We have further shown that Lp(a) blocks specifically carboxy-terminal lysine residues on the surface of fibrin. To further explore the role of apo(a) on the Lp(a) fibrin interactions, we have performed ligand-binding studies using a recombinant form of apo(a) that contains 17 kringle 4-like units. We have shown that recombinant apo(a) binds specifically to fibrin (Kd = 26 +/- 8 nM, Bmax = 26 +/- 2 fmol/well) and that this binding increases upon treatment of the fibrin surface with plasmin (Kd = 8 +/- 4 nM, Bmax = 115 +/- 14 fmol/well). Altogether, our results indicate clearly that binding of native Lp(a) through this mechanism may impair clot lysis and may favor the accumulation of cholesterol in thrombi at sites of vascular injury.

Apolipoproteins↗